1. Field of the Invention
The present invention relates to an inhibitor switch.
2. Description of the Related Art
There is a conventional inhibitor switch apparatus described in, for example, Japanese Patent Laid-Open No. 134672/1998 as shown by FIG. 16. The inhibitor switch 201 is provided with a plurality of fixed contacts 205 at a lower face of a pole disk 203 and a moving contact 209 is supported by a moving disk 207 movable relative to the pole disk 203. The moving contact 209 is provided with a plurality of contact arms 211 in a cantilever style. The respective contact arm 211 is brought into slidable contact with the respective fixed contact 205. A state of contact to the respective fixed contact 205 by the respective contact arm 211 is as shown by, for example, FIG. 17.
The respective fixed contact 205 is provided to the pole disk 203 formed by resin by insert molding and a bent contact portion 213 of the contact arm 211 is made slidable relative to the fixed contact 205. Further, an ON/OFF switch position 215 by slidable movement of the moving contact 211 relative to the fixed contact 205, constitutes a boundary of insert molding of the fixed contact 205 and the pole disk 203.
Therefore, in accordance with movement of the moving disk 207, the respective contact arm 211 is slidingly moved relative to the respective fixed contact 205 while in contact therewith, contact/non-contact of the contact arm 211 with respect to the fixed contact 205, is carried out by passing the ON/OFF switch position 215 and selective conduction of the respective fixed contact 205 can be ensured.
In this case, the contact portion 213 of the contact arm 211 is formed to bend and is brought into a substantially linear contact state relative to the fixed contact 205. Therefore, by determining the ON/OFF switch position 215 by accurately setting the boundary of the insert molding, switching between contact/non-contact of the respective contact arm 211 with respect to the respective fixed contact 205, can accurately be carried out.
However, the contact arm 211 is slidingly moved relative to the fixed contact 205 as described above and therefore, there poses a problem that the contact portion 213 of the contact arm 211 is ageingly worn and is brought into a face contact state as shown by FIG. 18. Moreover, an ON/OFF switch range H is enlarged, a time period during which the contact portion 213 rides on the ON/OFF switch position 115 is prolonged and hysteresis of a circuit is increased.
Particularly, in the case of an inhibitor switch used in a transmission case, oil is scattered and worn powder of an insulator or the like mixed into the oil is liable to be put between the contact portion 213 of the contact arm 211 and the fixed contact 205 and there is a concern that wear is progressed at an early stage such that the ON/OFF switch range H is increased at an early stage.
Further, there also poses a problem that the ON/OFF switch position 115 is extremely difficult to adjust on dies. That is, according to the above-described structure, when the ON/OFF switch position 115 is adjusted, an end portion of the fixed contact 205 is machined by, for example, {fraction (1/100)} mm, dies for insert molding must be adjusted in conformity therewith. Accordingly, both dies of the pole disk 203 and the fixed contact 205 need to change and there is a concern that it is extremely difficult to determine the ON/OFF switch position 115 by adjusting them both.
Further, in press-forming the fixed contact 205, droop 219 is caused as shown by FIG. 19A and burr 221 is caused as shown by FIG. 19B. Accordingly, when the ON/OFF switch position 115 is determined, an actual ON/OFF switch position 223 or 225 is shifted from the above-described ON/OFF switch position 115 by the droop 219 or the burr 221 and there poses a problem that it is extremely difficult to accurately adjust the ON/OFF switch position also in this respect.
The invention is aimed to provide an inhibitor switch apparatus capable of accurately maintaining an ON/OFF switch position and facilitating adjustment of the ON/OFF switch position even when wear is caused at a moving contact.
According to a first aspect of the invention, there is provided an inhibitor switch comprising a pole disk having a fixed contact, and a moving disk having a moving contact slidable relative to the fixed contact and movable relative to the pole disk, the inhibitor switch being arranged in a transmission case of an automatic transmission, with a speed change position of the automatic transmission being detected by the moving contact and the fixed contact, wherein the pole disk is projected with an insulator portion formed by an insulating member in correspondence with an ON/OFF switch position of the fixed contact constituting a boundary of contact and non-contact by sliding movement of the moving contact relative to the fixed contact; the moving contact includes a ride-on portion capable of riding on the insulator portion; and when the moving contact is slidingly moved relative to the fixed contact and the moving contact is disposed at the ON/OFF switch position of the fixed contact, the ride-on portion rides on the insulator portion, the moving contact is separated from and brought into non-contact with the fixed contact and when the ride-on portion comes down from the insulator portion, the moving contact is brought into contact with the ON/OFF switch position of the fixed contact.
According to a second aspect of the invention, there is provided the inhibitor switch according to the first aspect of the invention, wherein the ride-on portion of the moving contact includes a rounded portion for riding on; and the insulator portion includes a sliding face for making the rounded portion of the ride-on portion ride thereon and guiding the rounded portion.
According to a third aspect of the invention, there is provided the inhibitor switch according to the first or second aspect of the invention, wherein the moving contact includes a pair of contact portions in a cantilever shape simultaneously brought into elastic contact with the fixed contact; and the ride-on portion is arranged between the two contact portions and formed in a cantilever shape shorter than the contact portions.
According to a fourth aspect of the invention, there is provided the inhibitor switch according to the first or second aspect of the invention, wherein the moving contact includes a plurality of contact portions simultaneously brought into elastic contact with the fixed contact; and the fixed contact includes discharge portions for discharging a foreign object interposed between the two contacts from discharge ports provided at the fixed contact respectively in correspondence with the contact portions of the moving contact.
According to a fifth aspect of the invention, there is provided the inhibitor switch according to the fourth aspect of the invention, wherein the respective discharge portions in correspondence with the respective contact portions are arranged at positions shifted from each other in a sliding direction of the movable contact.
According to a sixth aspect of the invention, there is provided the inhibitor switch according to the fourth or fifth aspect of the invention, wherein the discharge portions are provided at vicinities of the ON/OFF switch position of the fixed contact.
According to a seventh aspect of the invention, there is provided the inhibitor switch according to any one of the fourth to sixth aspects of the invention, wherein the discharge port communicates with a through hole of the base disk.
According to the first aspect of the invention, in the inhibitor switch apparatus comprising the pole disk having the fixed contact and the moving disk having the moving contact slidable relative to the fixed contact and movable relative to the base disk, wherein the inhibitor switch apparatus is arranged in the transmission case of the automatic transmission and the speed change position of the automatic transmission is detected by the moving contact and the fixed contact, by projecting the insulator portion formed by the insulating member in correspondence with the ON/OFF switch position of the fixed contact constituting the boundary of contact and non-contact of the moving contact relative to the fixed contact, to the pole disk and providing the ride-on portion capable of riding on the insulator portion, at the moving contact, when the moving contact is slidingly moved relative to the fixed contact and the moving contact is disposed at the ON/OFF switch position of the fixed contact, it is possible that the ride-on portion rides on the insulator portion, the moving contact is separated from and brought into non-contact with the fixed contact and when the ride-on portion comes down from the insulator portion, the moving contact is brought into contact with the ON/OFF switch position of the fixed contact.
Therefore, by making the ride-on portion of the moving contact ride on the insulator portion or come down from the insulator portion, contact and non-contact of the moving contact relative to the fixed contact can firmly be carried out at the ON/OFF switch position of the fixed contact. That is, even when the moving contact is worn and contact to the fixed contact is spread from line contact to face contact, by making the ride-on portion of the moving contact ride on the insulator portion or come down from the insulator portion, the moving contact can make either non-contact or contact firmly at the ON/OFF switch position of the fixed contact. Therefore, an accurate inhibitor switch capable of maintaining detection of the accurate speed change position for a long period of time and having high durability can be provided.
According to the second aspect of the invention, in addition to an effect of the invention of the first aspect, the ride-on portion of the moving contact includes the rounded portion for riding on, the insulator portion includes the sliding face for making the rounded portion of the ride-on portion ride thereon and for guiding the rounded portion. Therefore, when the ride-on portion of the moving contact rides on the insulator portion, the rounded portion is not slidingly moved at one location of the insulator portion but slidingly moved along the sliding face of the insulator portion and the insulator portion can be prevented from being worn locally. Therefore, by making the ride-on portion ride on the insulator portion or come down from the insulator portions, the moving contact can firmly make contact and non-contact at the ON/OFF switch position of the fixed contact and a firm ON/OFF state can be maintained for a long period of time.
According to the third aspect of the invention, in addition to the effect of the invention of the first or second aspect, the moving contact includes the pair of contact portions in the cantilever shape simultaneously brought into elastic contact with the fixed contact. The ride-on portion is arranged between the two contact portions and formed in the cantilever shape shorter than the contact portions and accordingly, the rigidity of the ride-on portion can be ensured while bringing the moving contact into elastic contact with the fixed contact. When the ride-on portion rides on the insulator portion or comes down from the insulator portion, bending of the ride-on portion is restrained and contact and non-contact operation of the moving contact can firmly be carried out at the ON/OFF switch position of the fixed contact.
According to the fourth aspect of the invention, in addition to the effect of the invention of the first or second aspect, the moving contact includes the plurality of contact portions simultaneously brought into elastic contact with the fixed contact and includes the discharge portions for discharging the foreign object interposed between the two contacts from the discharge ports provided at the fixed contact respectively in correspondence with the contact portions of the moving contact and accordingly, when the moving contact comes down from the insulator portion, even when the foreign object is interposed between the moving contact and the fixed contact, by making the movable contact slidingly move relative to the fixed contact, the foreign object between the two contacts can be discharged from the discharge ports to the discharge portions. Therefore, contact of the moving contact to the fixed contact can firmly be ensured.
Further, since the moving contact includes the plurality of contact portions simultaneously brought into elastic contact with the fixed contact, even when the foreign object is interposed between either of the contact portions and the fixed contact, by utilizing elasticity of the moving contact, other contact portions can firmly be brought into contact with the fixed contact and regardless of whether a foreign object is interposed, contact of the moving contact to the fixed contact can firmly be ensured.
According to the fifth aspect of the invention, in addition to an effect of the invention of the fourth aspect, the respective discharge portions in correspondence with the respective contact portions are arranged at the positions shifted from each other in the direction of sliding the moving contact and therefore, even when the foreign object is interposed between either of the contact portions and the fixed contact, by discharging the foreign object by either of the discharge portions the positions of which are shifted from each other, contact between the contact portion and the fixed contact can be ensured. Therefore, the foreign objects can be restrained from being simultaneously interposed between both of the contact portions and the fixed contact and the contact portion and the fixed contact can firmly be brought into contact with each other.
According to the sixth aspect of the invention, in addition to the effect of the invention of the fourth or fifth aspect, the discharge portions are provided at vicinities of the ON/OFF switch position of the fixed contact and therefore, when the moving contact comes down from the insulator portion to the ON/OFF switch position of the fixed contact, even when the foreign object is interposed between the contact portion of the moving contact and the fixed contact, by starting to move the moving contact slidingly, the foreign object is immediately discharged from the discharge port and the moving contact can firmly be brought into contact with the fixed contact.
According to the seventh aspect of the invention, in addition to the effect of the invention of any one of the fourth to sixth aspects, the discharge port is communicated with the through hole of the base disk and therefore, the foreign object discharged from the discharge port to the discharge portion can be discharged from the through hole of the base disk to outside of the base disk and the foreign object can firmly be discharged.